Side Effects
by latessitrice
Summary: Erskine's formula did have one problematic effect on Steve's body. Darcy's willing to help in the name of science, if only he'd ask.


**I know I have other stories to be updating, but the world has gone to shit and apparently this is my happy place. Was going to be a one shot, but we know I'm terrible at sticking to those.**

 **This is alpha/omega without the omega and with two supersoldiers. I'm going to do my damnedest to make sure everything's consensual even with the hormones flying around, which is why I haven't ticked any archive warning. Eventual Wintershieldshock.**

 **Side Effects**

"You may feel some nausea, but that should be the only immediate side effect." Doctor Cho gives Steve a reassuring smile and removes the syringe from his arm, where she's just injected him with her latest formulation.

"Can't be any worse than when they first gave me the serum," he replies, returning her smile and staring up at the ceiling of the medical booth. The little pads she's stuck wires to his skin with are itchy, though he's sure it's only because he knows they're there.

"What about other side effects?" From his prone position, Steve can't see Natasha, only hear her question to the doctor. He jolts, unaware of her presence until she spoke.

"Aren't you supposed to discuss this stuff before you stick him with chemicals?"

Steve knows this voice too; another intruder. He's unsure if the warm flash he feels is an unexpected side effect, or the realization of who has crept in with Natasha. A very particular someone who he does not need knowing why he's here, or want around if it goes south.

"Steve, you've met Darcy, right?" Natasha says. "She has a good point."

"Captain Rogers and I have had a full discussion about the other potential effects of the medication," Doctor Cho replies. "However, I am going to need both of you to leave the room. This isn't a spectator sport."

"I'm only here to offer Steve support," protests Natasha. "It's not like him to need medical attention unless he's injured." There's barely disguised curiosity in her voice.

"If he wanted you here, he'd have asked you to accompany him. Please go." The tone in the doctor's voice does not invite negotiation, although she does soften the command with, "You can wait outside if you must."

"I only came to dish out lollipops," Darcy says in a small voice. "I made Janey go take a nap so I don't have anything else to do."

Steve gets the impression there's a silent debate going on he can't see, but the room's started swimming so he's reluctant to move his head and find out. Instead, Natasha apparently decides to leave, but not before granting him with an ominous parting shot.

"I'll be right out here, waiting."

She must hear his responding sigh, but then there is privacy again, even if it's only until she can question him later. Steve briefly wonders if Natasha would actually go looking for electronic means into his medical records to answer this mystery, but he trusts her enough not to. He knows she values his trust too much to destroy it like this.

"Darcy left you a lollipop behind," says Doctor Cho. "Cherry, I think. It might help settle your stomach if you do feel ill."

He shakes his head and regrets it. "Actually, I think I will take it."

The doctor's face appears in his field of vision, wrinkled with concern. "Your body temperature has shot up. I need to take a blood sample to check your hormone levels." All it takes is a pinprick at the end of his finger, and then the little silver tube she holds beams the results to the computer screen. It means nothing to him, but everything to her, and she shoves the lollipop into his hand as she scribbles notes down.

"Well," she eventually says, "your immune system is burning through the new serum and it's causing a spike in your hormone levels. It may just be that your immune system will accept the changes to your DNA and settle down soon enough. Otherwise, we'll need to keep working on the formula to find something your body rejects."

"Which is looking more likely right now?"

"Door number two, I'm afraid. Especially with the way your temperature keeps rising."

Steve already knows where this is heading, except it's faster than it's ever happened before. He's not only feeling hot, but every inch of his skin is hypersensitive and prickling. Other senses are gearing up too: the light above is head is suddenly too bright, and there's a scent in the room he couldn't have picked out a few minutes ago. Now he can: cherry blossom perfume, warmed on Darcy's skin. "I know, doc. I think you need to get me to a containment room ASAP. I'm about to go into rut."

As side effects went, Erskine's serum had been pretty forgiving to Steve. He'd hadn't ended up with a red skull, or suffered much beyond the initial transformation. The only snag, as it were, had emerged in the battlefields of Europe. Emotions had been running high, and so were his hormones. Howard Stark had been the first to spot the problem, when Steve spiraled into a fit of aggression, agitation, and discomfort. He'd been gruff and withdrawn, snapping at anyone who came near and yet desperate for human contact.

"Ah, this possibility was buried in Erskine's notes," Stark had announced. "But you were on tour all those months with the girls and nothing happened, so I figured it wasn't an issue."

"What possibility?" Steve had growled back, before being distracted by Peggy's arrival into the tent. Her scent hit him first, the sharp tang of Imperial Leather soap and the warm wool of her uniform, and though he knew Stark kept talking, he wasn't listening to a damn word. Instead, when Stark pulled Peggy aside to have a hushed conversation with her, the irritation inside him threatened to spill over into actual violence.

"Oh, for heaven's sake!" Peggy's voice had brought him back to the present, and he watched her crimson lips move as she continued speaking. "Are you absolutely sure?"

"Look at him, Peg," was Stark's reply. Later, much later, Peggy had told him he was a sight, sat on that cot: flushed cheeks and swollen mouth, from where he'd been biting it, eyes so blown they looked black, fists clenched, his expression raw and hungry. She'd been in two minds about what to do: knock him out with a swift right hook, or put him out of his misery by giving him what he really wanted. She'd decided he was too thickheaded to make the first option feasible, and instead had bundled him out of the tent and into a vehicle commandeered from Stark, until they were somewhere far more private.

A secret mission, was the official word. So official that the truth had never been written down, and of course Peggy had never told another soul. Those three days were the only significant time he'd been able to spend with Peggy, particularly alone, and it still ached inside that it'd been driven by a biological need. Instead of being able to properly court her, they'd had a few days in a cabin in the forest, and he'd been almost entirely consumed by the need to be inside her.

After the ice, the problem seemed to go away. Three whole years with no issues, right until they moved into the Avengers' facility upstate. Now, in the space of a few months, he's been hit by the ruts—as Doctor Cho has labeled them—four times. They're becoming more frequent, and he's desperate for a way to control them.

Doctor Cho was the obvious choice, but her initial attempts at stabilizing his hormones have been utter failures. The best Steve can do is lock himself away, so he doesn't accidentally hurt anyone when he isn't in full control of his temper.

It also ensures that no one gets to see him acting like a dog in heat. Without Peggy around to take the initiative, his only companions are a lot of lubricant and tissues. It's not what his body wants, but it gets him through.

This time, after he rouses from his stew of hormones, takes a shower, and dresses, he signals for Doctor Cho to release him from the containment room, wondering how long it's been. The room is actually basic set of quarters housed in the medical labs which allows the doctor to monitor his stats while keeping him in one place, when his facility to be reasoned with is diminished. He hears the electronic lock on the door click open, and lets himself out.

Doctor Cho is waiting in the lab beyond, finishing typing up some figures, and she gestures to the Starkphone he left in her care. "I made your apologies as best I could."

She's getting good at this, sending messages as Steve while pretending he's out tracking his former friend in the wilderness. In a few minutes, he'll need to return to the main facility and pretend that he's returned home empty-handed once more.

The hollowed-out feeling he's left with after his rut should help with that performance.

A glance at the phone tells him he's been out of it for five days, more or less, and that means the problem is only getting worse. He's ready to go, unwilling and unable to make eye contact with the doctor after all she's witnessed, even if she is kind and far from judgmental. Instead, she speaks.

"I have a theory," she says, pulling up charts on the screen behind her. He's seen enough of these charts to know they're his hormone levels.

"You do?"

"And it is just a theory, but it's the best one I have for now." She pauses and zooms in on one of the charts, a jumble of squiggly lines to him. "The formula really shouldn't have caused that reaction in you, not on its own. The worst case scenario was that your body would burn through it and render it inert. I believe an outside stimulus caused your hormones to spike like they did."

"Such as?"

She raises an eyebrow at him and waits for him to put the pieces together. He blushes and stares at the floor, unwilling to voice his suspicions out loud. Luckily, she confirms the rest of her theory for him. "I think the hormonal spikes are driven by sexual attraction. That's why there's no pattern to them: unless you are exposed to someone you are strongly attracted to, and I would suspect regularly exposed to them, your hormones remain stable."

Steve doesn't say a word. He's very interested in his shoelaces.

"Sexual release might be the control you're looking for, and abstention will result in the ruts becoming more frequent. That's the only pattern I can see, based on what you told me about your original experience, and the data I have."

"So it's going to get worse?"

"Or you could ask Natasha on a date."

That, finally, has him looking up at the doctor and offering her a bashful smile. "Nah, I don't think that will solve the problem at all, doc. I've known Natasha as long as I've been out of the ice."

The doctor smiles. "Then you should ask her young friend out. I'm sure she'll be amenable—and it's about time you started calling me Helen like everyone else."

Steve thanks her and makes his getaway, planning on taking a service corridor back towards his quarters. At least with Tony in Manhattan most of the time, Steve can fly under the radar more when these things occur. Helen's words are tattling around his skull, but he doesn't take them seriously. Not when his life is the mess that it is. It wouldn't be fair to drag someone else into it, not to solve his little problem. Even if he's been thinking of her a lot more, waking up drenched in sweat from dreams of dark curls and pouty lips—not red ones, but all pink and plump—it's his issue to deal with. He shouldn't take Darcy's kindness and friendly demeanor for more than it is.

He almost makes his escape, but when he skulks through a set of double doors out of medical, Natasha's voice catches him by surprise.

"I knew you weren't in Norway!"

Well, she did tell him she'd be waiting.


End file.
